276 THE AMERICAN NATURALIST. [Vol. XXXVIII. 



admits the possibility that the ear may also be in some degree an 

 organ of hearing. The fact that certain fishes do respond to 

 what are beyond question sound vibrations in water was demon- 

 strated independently by Zenneck (:o3) for three fresh-water 

 species, Leiicisciis riitiliis, L. dobtda, and Alburniis lucidiis, and 

 by Parker (:03*, :03^) for a salt-water species, Funduhis hetero- 

 clitiis. Parker further showed that this response was dependent 

 on the presence of a functional internal ear, and that, therefore, 

 this species could be said to hear. But he could not get any 

 response to sound from the smooth dogfish, and so was led to 

 conclude that different fishes might differ widely in this respect, 

 some possessing, some lacking, a true sense of hearing. Since 

 none of the recent investigators w^ho favor the view that fishes 

 hear, have tested the species which, in Kreidl's hands, yielded 

 negative results, it seemed desirable, in the light of recent work, 

 to examine the goldfish again ; and this I have undertaken to do. 

 This problem was suggested to me by Professor G. H. Parker, 

 and I am indebted to him for help, suggestions, and criticism 

 throughout the series of experiments. 



II. Methods. 



In determining whether or not a fish has a sense of hearing 

 it must be borne in mind that the responses to sound may be 

 very slight and easily confused with responses to other stimuli ; 

 and, further, that, although the absence of response does not 

 necessarily mean absence of hearing, the consistent occurrence 

 of a response is fair evidence of the presence of this sense. To 

 test normal goldfishes satisfactorily, it was necessary to isolate 

 them from all other disturbances and to apply the sounding 

 mstrument as directly as possible to the water, but without caus- 

 ing any gross mechanical vibration. The apparatus which I used 

 was an aquarium, some 30 cm. wide, 35 cm. long, and 15 cm. 

 deep. The two sides were of glass, and the ends and bottom of 

 clear white pine. The aquarium was placed on a wooden table 

 which stood with its feet on many thicknesses of soft paper, thus 

 isolating it from vibrations which might otherwise reach it 

 through the floor. The bottom of the aquarium was covered on 



